As computers have advanced, it is common to connect a plurality of computers to construct a LAN (Local Area Network), so that information on files and data is shared, peripheral devices such as printers are shared, and information exchange such as electronic mail and data transfer is performed.
In a conventional LAN, each computer is connected by wires by using optical fibers, coaxial cables, or twisted-pair cables. In such a wired LAN, however, construction work is required for connection. It is difficult to construct a LAN with ease, and the cabling is complex. Furthermore, after a LAN is constructed, the range in which devices can move is limited by the length of the cable, and this is inconvenient.
In connection with the above, as a system in which a user is released from the wiring of a LAN associated with a conventional wired method, a wireless LAN has attracted attention. According to this type of wireless LAN, in a work space such as in an office, since most of the cables can be omitted, terminals such as personal computers (PCs) can be moved relatively easily.
As a method of constructing a wireless network, a method in which one of the wireless transmission apparatuses forming the wireless network is used as a control station (coordinator) of the network is conceived.
For example, in Japanese Unexamined Patent Application Publication No. 2000-138685 which has already been assigned to the applicant of the present invention, a wireless transmission control method in which a wireless network is automatically configured by making all of the stations have a function for operating as a control station is disclosed.
According to the wireless transmission control method described in that publication, the communication station which is selected as a central control station determines stations with which each terminal station within the wireless network can directly perform wireless communication. When it is detected that wireless communication can be performed with a communication station in which the number of terminal stations is greater than the number of stations which can directly perform wireless communication with the central control station, the communication station performs a process for changing the detected terminal station to a central control station. That is, a station suitable for controlling each communication station within the wireless network is automatically selected as a central control station, and thus the wireless network is automatically constructed suitably. Therefore, even if the control station is not set in advance, it is possible to cause a specific apparatus within the network to operate as a control station, making it possible to construct a wireless network in which wireless transmission apparatuses are placed freely.
A method is further conceived in which a wireless transmission apparatus suitable as a control station is selected and it is made to function as a control station with priority.
For example, in Japanese Patent Application No. 2001-174766 which has already been assigned to the applicant of the present invention, a wireless communication system capable of causing a wireless transmission apparatus determined by a user to operate as a control station with priority is disclosed.
According to the wireless communication system described in that specification, setting is performed beforehand in a communication apparatus which is desired to be set as a control station so as to function as a control station with priority. In a case where this function is set in a plurality of communication apparatuses, a control station is selected according to the number of apparatuses capable of performing communication with the apparatus. Therefore, when a control station is determined automatically to construct a wireless network, it is possible to cause the wireless transmission apparatus set by the user to operate as a control station with priority.
However, in these conventional wireless network construction methods, in general, since an apparatus which serves as a control station is simply specified, it is not possible to specifically exclude a transmission apparatus which is not suitable as a control station.
For example, even if a terminal station is an apparatus which is not suitable as a control station because its computation function is poor, such as headphones, or if a terminal station is an apparatus which is not suitable as a control station whose power consumption is large because it is battery driven, there is still a possibility that the apparatus is selected as a control station in the above-described wireless network construction method.
Furthermore, even when a function capable of serving as a control station with priority is provided, in a communication environment in which only wireless transmission apparatuses that are not provided with a function capable of serving as a control station with priority exist, there is a problem in that a wireless network cannot be constructed unless a control station is selected from among these apparatuses.
For this reason, a problem arises in that a wireless transmission apparatus that is not suitable as a control station is selected when constructing the wireless network.